An internal combustion engine is used as a power system for an automobile. The internal combustion engine includes a plurality of actuators such as a throttle, an ignition device, and a fuel injection device, and can achieve desired torque by having these actuators cooperate with each other. Since the torque of the internal combustion engine is determined by the operations of the actuators, it is necessary to determine how to operate the actuators for torque control purposes.
It is conceivable that torque control may be exercised by distributing a target torque to each actuator and operating each actuator in such a manner that the internal combustion engine achieves the distributed target torque. When torque control is to be exercised by using, for instance, the throttle and ignition device, the intended purpose can be accomplished by controlling the throttle opening in accordance with the target torque for the throttle and controlling the ignition timing in accordance with the target torque for the ignition device. A low-pass filter or other signal processing filter can be used to distribute the target torque to each actuator.
A hybrid power system disclosed in Patent Document 1 includes an internal combustion engine and a motor as power units. This system uses a low-pass filter as a means of distributing a target transmission torque to a clutch and motor. More specifically, the low-pass filter eliminates a high-frequency signal component, which cannot be covered by clutch control, from the target transmission torque supplied to a clutch control device. Clutch control is then exercised to achieve the target transmission torque from which the high-frequency signal component is eliminated. In addition, motor control is exercised to implement the high-frequency signal component, which is eliminated by the low-pass filter.    Patent Document 1: JP-A-1999-159364    Patent Document 2: JP-A-1998-23609    Patent Document 3: JP-A-1993-163996